Re-direction of vapor flow across tubular condensers

ABSTRACT

Vapor flow-diverting devices that re-direct upwardly flowing vapor, for example, in a downward direction across condenser tubes disposed in the upper or top section of a vapor-liquid contacting apparatus, are described. These devices are particularly beneficial in tubular condensers within distillation columns and may be used in combination with other associated equipment (e.g., a deflector plate and divider plate) as well as in combination with the tube surface enhancements to improve the heat transfer coefficient.

FIELD OF THE INVENTION

The invention relates to heat exchangers such as tubular condensers withtubes that may extend horizontally or vertically within a distillationcolumn. The heat exchangers have a vapor flow-directing device tore-direct vapor flow (e.g., in the downward direction) across a sectionof the condenser tubes to reduce the possibility of entrainment ofcondensed liquid.

DESCRIPTION OF RELATED ART

Heat exchangers are prevalent in refining, petrochemical, and otherindustrial applications in order to efficiently transfer heat availablein one process fluid to another fluid, such that the overall utilityrequirements are reduced. The advantages of using heat exchangers, forexample, to optimize the recovery of heat and thereby minimize the costsassociated with outside sources of cooling/refrigeration media (e.g.,cooling water) and/or heating media (e.g., fuel gas) are wellrecognized. The art has continually sought to improve the performance ofheat exchangers by achieving the closest possible approach to theequilibrium level of heat transfer between two fluid streams at thelowest possible equipment, operating, and maintenance costs.

Heat exchange is commonly carried out, for example, between a relativelyhot reactor effluent fluid and a relatively cold reactor feed fluid. Acombined reactor feed/effluent heat exchanger in this case canbeneficially add at least a portion of the heat required to raise thereactor feed to a specified reaction temperature and at the same timeremove at least a portion of the heat required to cool the reactoreffluent for further processing or storage. A specific application forheat exchangers involves their use within (rather than external to)other processing equipment such as vapor-liquid contacting apparatusesand even reactors. In the case of a reactor, for example, a heatexchanger within a vapor space above a reaction zone may beneficiallycondense evaporated reactants while allowing the removal of uncondensedvapors, particularly product vapors.

Vapor-liquid contacting apparatuses known to utilize internal heatexchangers, and particularly condensers, include distillation columns.The specific operating conditions of distillation columns employinginternal heat exchangers may vary significantly in order to accomplish awide range of component separations from vastly different types ofmixtures that may be subjected to distillation. Examples of distillationcolumns include those used in a number of column separations such asstripping and rectification, as well as those used in various forms ofdistillation such as fractional distillation, steam distillation,reactive distillation, and distillation in divided wall columns. Theseseparation processes may be operated using distillation columns ineither batch or continuous modes, with common design objectives beingthe reduction in installed and operating costs. The equipment andutilities required for the supply and removal of heat to and from thecolumn significantly impact these costs in many cases.

Various benefits may be achieved from installing heat exchangers insidedistillation columns or other apparatuses, rather than external to thecylindrical column shell. These benefits may be appreciated withreference to the operation of conventional external heat exchangers,which require removing a stream from the column, passing it through theexternal exchanger to supply or remove heat, and returning at least partof the heated or cooled stream back to the column. For example, overheadvapor may be withdrawn from a top or overhead section of the column(e.g., after rising from a top contacting tray) and passed to anexternal heat exchanger, namely a condenser or partial condenser, thatcondenses liquid from the withdrawn vapor, a portion of which is thengenerally returned (e.g., using a pump) to the column as reflux. Inaddition to an external heat exchanger and pump, the overhead systemfrequently also comprises a receiver vessel to separate the condensedliquid from uncondensed vapor, as well as the associated pipes, valves,and instrumentation. In a manner analogous to that of a condenser,external reboiler heat exchangers may also provide vapor to (rather thanremove vapor from) the column by heating a liquid stream removed fromthe bottom section of the column. Likewise, vapor and liquid streams maybe withdrawn from a central section between the top and bottom sectionsof the column, heated or cooled using an external heat exchanger, andreturned to the column. In each case, the equipment requirements arecomparable.

By locating a heat exchanger within a vapor-liquid contacting apparatussuch as a distillation column, some equipment (e.g., an overhead refluxpump) and the associated supporting structure can be eliminated, therebysaving both equipment cost and space. Additionally, the pressure dropthrough an internal heat exchanger can be lower than that for anequivalent external heat exchange system. This becomes an importantfactor when the column is operated at nearly atmospheric or evensub-atmospheric pressure, for example in cases where the columntemperatures are limited due to heat sensitivity of the mixture beingprocessed in the column.

Representative examples of low pressure distillation columns in whichinternal condensers have been successfully employed include those usedin the product recovery sections in the commercial production of phenolvia cumene oxidation, as well as in the upstream production of cumenevia benzene alkylation. Also, U.S. Pat. No. 2,044,372, U.S. Pat. No.4,218,289, U.S. Pat. No. 5,507,356, and DE 198 30 163 A1 describe theuse of various heat exchangers inside columns to at least partiallycondense vapor in the top section of columns. U.S. Pat. No. 2,044,372describes the use of a vertical submerged condenser between a lowpressure section and a high pressure section of a single column.

A particular type of heat exchanger that may be used internally (or thatis otherwise commonly employed commercially), is a tubular exchangercomprising a bundle of tubes, whereby heat is transferred between fluidexternal to the tubes and fluid passing through the tubes. So-called“stabbed-in” tube bundles have advantages over internal welded platebundles in terms of their ease of removal for maintenance orreplacement. In the case of stabbed-in tubular condensers, with thetubes being oriented horizontally or vertically in the top section of adistillation column, overhead vapor in the column is condensed on theoutside or external surface of the tubes. In view of the desirability oftheir use, there is an ongoing need in the art for improvements ininternal tubular heat exchangers and particularly those disposed withina vapor-liquid contacting apparatus such as a distillation column.

SUMMARY OF THE INVENTION

The present invention is associated with the discovery of improvementsin heat exchangers comprising tube bundles and particularly internaltubular condensers disposed within vapor-liquid contacting apparatusessuch as distillation columns. Aspects of the invention relate to the useof vapor flow-directing devices disposed within columns and surroundingor substantially surrounding (e.g., over a surrounding area except foran inlet for downwardly flowing vapor, a non-condensed vapor outlet, anda condensed liquid outlet) tubes within the column that are used in tubebundles of internal tubular condensers as discussed above. Vaporflow-directing devices can be used, for example, as a “shroud” or ameans for protecting all or at least a section, such as a co-current,vapor-liquid contacting section, of the tubes within the column frombeing directly impacted by the rising vapor that is ultimately cooled onexternal surfaces of the tubes. Vapor flow-directing devices, bydirecting vapor, for example, in the downwardly flowing direction overat least the co-current contacting section of tubes therefore allow inthis section, vapor and condensed liquid to flow co-currently. Thisreduces or even eliminates the risk of entrainment of condensed liquidby vapor that, in the absence of the vapor flow-directing device, wouldnormally flow upwardly during contact with the external surfaces of thecondenser tubes.

Co-current flow of downwardly flowing vapor and liquid that is condensedon external surfaces of the condenser tubes is generally achieved byhaving a downwardly flowing vapor inlet of the vapor-flow directingdevice above at least the co-current contacting section of the tubes.Separation of the vapor that is not condensed (non-condensed vapor),from the liquid that is condensed as a result of heat exchange acrossthe external surfaces of the tubes, is carried out in a vapor-liquiddisengagement volume. The disengagement volume, in addition to the tubesor a portion of the tubes within the column, is generally encompassed orsubstantially surrounded by the vapor flow-directing device. Accordingto a representative embodiment, the vapor-liquid disengagement volume isbelow the condenser tubes or portion thereof within the column. In thiscase, a deflector plate may be positioned below the tubes and in thedisengagement volume to improve the vapor-liquid separation afternon-condensed vapor and condensed liquid flow co-currently past theco-current contacting section of the tubes. The deflector plate mayextend horizontally or may be somewhat inclined from the horizontal toensure that condensed liquid impacting this plate drains freely througha condensed liquid outlet leading back into the column (e.g., back tothe top contacting tray, plate, or stage). According to otherembodiments, a divider plate may extend into the vapor flow-directingdevice to separate a co-current contacting section of the tubes, withina contacting volume, from a disengagement section of the tubes, withinthe vapor-liquid disengagement volume.

Accordingly, further embodiments of the invention are directed toapparatuses for vapor-liquid contacting. The apparatuses comprise avertically oriented column having disposed therein a plurality ofcondenser tubes (e.g., extending vertically or horizontally). Theapparatuses also comprise a vapor flow-directing device disposed withinthe column and having a vapor inlet above at least a co-currentcontacting section of the tubes and defining a vapor-liquiddisengagement volume. The apparatuses further comprise a non-condensedvapor outlet external to the column and in communication with thevapor-liquid disengagement volume and a condensed liquid outlet internalto the column and in communication with the vapor-liquid disengagementvolume.

According to a particular embodiment, the vapor-liquid disengagementvolume is below the tubes, and, in this embodiment, a deflector platemay be positioned below the tubes and within the vapor-liquiddisengagement volume. The deflector plate may, for example, be above thenon-condensed vapor outlet and extend horizontally or at an incline. Inother representative embodiments, the apparatus as described above mayfurther comprise a divider plate extending into the vapor flow-directingdevice and dividing the co-current contacting section of the tubes, in acontacting volume, from a disengagement section of the tubes, in thevapor-liquid disengagement volume.

Representative apparatuses include distillation columns as well asreactors, including those used in reactive distillation. Other types ofreactors are those which may benefit from internally condensing at leasta portion of vapors within the reactor. For example, it may be desiredto condense a condensable portion of the reactor effluent within thereactor to provide an internal reflux and/or avoid all or at least partof the downstream cooling requirements.

Further aspects of the invention relate to the use of condenser tubes inthe apparatuses described above, in which the tubes have one or moresurface enhancements that improve their performance within a section(e.g., an overhead section) of the length of a vertically orientedcolumn. The surface enhancement(s) of the tubes beneficially improve(s)their heat transfer coefficient and consequently the overall heatexchange capacity of an internal tubular condenser bundle of a givensize that employs these tubes. This higher capacity in some instances(e.g., in the case of large columns and/or columns operating in lowpressure drop/low mass velocity regimes) can overcome the requirement touse more costly heat exchangers such as welded plate or external heatexchangers. In particular, the tube surface enhancements describedherein can increase the heat transfer coefficient of tubes used in atubular condenser such that the required exchanger area is reduced tobelow that which corresponds to a practical size limit (e.g., about 1.5meters (5 feet) diameter of the tube bundle) or weight limit forinstallation at the top of a distillation column.

Further embodiments of the invention are therefore directed toapparatuses for vapor-liquid contacting having tubes with surfaceenhancements to improve heat transfer. The apparatuses comprise avertical or substantially vertical column (e.g., a cylindrical columnhaving an axis that is aligned vertically or within about 5 degrees ofvertical). The column contains or has disposed therein a plurality ofcondenser tubes or a tube bundle (e.g., in the form of a U-tube bundlewith U-shaped individual tubes) of the internal tubular condenser and avapor flow-diverting device as described above. According to particularembodiments, the tubes extend substantially horizontally or otherwisesubstantially vertically over a section of the column length, forexample an overhead section near the top of the column. All or at leasta portion of the condenser tubes have external surfaces comprising oneor more surface enhancements to improve the heat transfer coefficient ofthe tubes.

Representative surface enhancements include shaped recessions,circumferentially extending fins, axially extending fins, or acombination of these. In the case of circumferentially extending fins,the fins may be characteristic of those used for “low finned” tubes,with the fins having a height from about 0.76 mm (0.03 inches) to about3.8 mm (0.15 inches). Circumferentially extending fins generally referto a plurality of “plates” that are spaced apart (e.g., uniformly or atregular intervals) along the axial direction of the tube. The plates ofcircumferentially extending fins, in an alternative embodiment, may beprovided by a single, continuously wound, helical spiral rather thandiscreet extensions. In either case, the plates often each have an outeredge (or outer perimeter), with a single tube extending through centralsections of a plurality of plates. The outer edges of the plates may becircular or may have some other geometry, such as rectangular orelliptical. In the case of circumferentially extending fins, furthertube surface enhancements can include one or more notches on the outeredges of all or a portion of these fins or plates, where the notches maybe spaced apart radially about the edges, for example, in a uniformmanner or at a constant radial spacing. In other embodiments,non-uniform radial spacing may be used. In the case of tubes used in avertically aligned tube bundle of a condenser, it may be desirable toalign the notches axially with respect to adjacent fins (i.e., theimmediately higher and/or lower circumferentially extending fins). Theaxial alignment of these notches, such that they may be superimposedwhen viewed axially, can improve condensate drainage, especially whenthe tubes are oriented vertically.

In the case of shaped recessions on the tube surface, all or at least aportion of the recessions may extend axially (e.g., in the form of oneor more elongated troughs) or otherwise be aligned in one or moreaxially extending rows (e.g., in the form of a plurality of discreet,smaller recessions). One or more axially extending fins may also be usedto improve the heat transfer coefficient of the tubes, alone or incombination with the shaped recessions and/or circumferentiallyextending fins. Combinations of surface enhancements (e.g., axiallyextending recessions and/or axially aligned rows of recessions, togetherwith circumferentially extending fins), are generally all located in thesame region of the tubes used for heat transfer, for example the regionextending vertically or horizontally over a section of the length of adistillation column.

Alone or in combination with surface enhancements, the tubes themselves,while extending in a generally linear direction, may have, in at leastone region of the tubes used for heat transfer as described above, anon-linear central axis, which can provide a non-linear internal flowpath for fluid flow through the tubes. For example, the tubes, as wellas their internal central axes, may have a wave, jagged, or helical(coiled) shape to increase pressure drop and/or fluid mixing. Otherwise,an overall helical fluid flow path can be provided, for example, in thecase of a flattened or eccentric profile tube (e.g., having arectangular cross-section or otherwise an oval-shaped or ellipticalcross section) that has a twisted tube geometry (i.e., such that a majoraxis of the cross-sectional shape, for example the major axis of anellipse, rotates clockwise or counterclockwise along the lineardirection of the tube). In the case of a twisted tube geometry, thecentral axis of fluid flow may be linear or non-linear (e.g., helical).Adjacent tubes extending generally linearly, for example in adistillation column section where heat transfer takes place, but havinga wave, jagged, or helical shape or a twisted tube geometry may have aplurality of external contact points with adjacent tubes, with thesecontact points possibly being evenly spaced apart by regions where theadjacent tubes are not in contact. Such spaced apart contact points withone or more adjacent tubes can physically stabilize the positions of thetubes and even avoid the need for baffles or tube supports.

Alternatively, an enhanced condensing layer (ECL) may be applied to theoutside or external surfaces of the tubular condenser tubes as anothertype of surface enhancement. Examples of ECLs include textured surfaces,chemical coatings that improve drop-wise condensation, nano-coatings,etc.

In addition to their exterior surfaces, the tube internal surfaces maybe modified to improve heat transfer capability. For example, all, amajority, or at least a portion of the tubes in the tube bundle may haveinternal surfaces, at least in a region of the tubes that extends (e.g.,vertically or horizontally) over a section of the column length, ontowhich a coating is bonded. If a coating is used, it is generally bondedto at least a region of the tubes (e.g., where condensation occurs onthe external tube surfaces) having the surface enhancement(s), asdiscussed above, on outer or external surfaces. A representativeinternal tube surface coating comprises a porous metallic matrix thatcan improve the internal heat transfer coefficient of the tube andconsequently the overall heat exchange capacity of a condenser using thetubes. Some suitable coatings are referred to as enhanced boiling layers(EBLs), which are known in the art for their applicability to heattransfer surfaces on which boiling occurs, and particularly for theirability to achieve a high degree of heat transfer at relatively lowtemperature differences. An EBL often has a structure comprising amultitude of pores that provide boiling nucleation sites to facilitateboiling.

An EBL or other coating may be applied to the inside or internalsurfaces of tubular condenser tubes. A representative metal coating isapplied as described, for example, in U.S. Pat. No. 3,384,154. Thecoated metal is subjected to a reducing atmosphere and heated to atemperature for sufficient time so that the metal particles braze orsinter together and to the base metal surface. An EBL may also havemechanically or chemically formed reentrant grooves as described, forexample, in U.S. Pat. No. 3,457,990. Other known methods of applyingcoatings and EBLs in particular to metal surfaces, such as the internalsurfaces of metal tubes, that may be used include those described in GB2 034 355, U.S. Pat. No. 4,258,783, GB 2 062 207, EP 303 493, U.S. Pat.No. 4,767,497, U.S. Pat. No. 4,846,267, and EP 112 782.

In addition to EBLs, another internal enhancement for condenser tubesinvolves the use of one or a plurality of ridges, which may, forexample, be in the form of a spiral or multiple spirals. Such ridges maybe used to further improve the transfer of heat, and particularlysensible heat, across the internal tube surface. Internal ridges may beused alone or in combination with other features of condenser tubes asdescribed herein. Further internal enhancements include twisted tape,wire matrix inserts (e.g., from Cal-Gavin Limited, Warwickshire, UK),and other in-tube heat transfer devices that can enhance the tubesideheat transfer coefficient.

Other embodiments of the invention are directed to tube bundles for acondenser comprising tubes and used in conjunction with a vaporflow-diverting device as described above. According to particularembodiments, a least a portion of the tubes, in an axially (e.g.,vertically or horizontally, depending on the orientation of the tubebundle) extending section, comprise shaped recessions on their externalsurfaces as surface enhancements. At least a portion of the shapedrecessions extend axially or are aligned in one or more axiallyextending rows (e.g., extending in the same or generally the samedirection as the tubes, or the central axes of these tubes). The use ofaxially extending shaped recessions (e.g., in the form of troughs) mayresult in the formation of axially extending ridges, as in the case of afluted tube. According to particular embodiments, the tubes furthercomprise one or more axially extending fins in the axially extendingsection (i.e., the same section as the shaped recessions). According toother embodiments, at least a portion of the tubes have a non-linearcentral axis and/or a twisted geometry, as discussed above, in theaxially extending section, and optionally a plurality of spaced apartpoints of external contact with adjacent tubes. According to furtherembodiments, the tubes, at least in the axially extending section, haveinternal surfaces having a coating (e.g., a porous metallic matrix asdiscussed above) bonded thereon in the axially extending section.

Further aspects of the invention relate to the use of any of thecondenser tubes as described above in tube bundles, in conjunction withthe vapor flow-diverting device as described above, for heat exchangeapplications. Accordingly, embodiments of the invention are directed tomethods of indirectly exchanging heat between two fluids, a first fluidand a second fluid, comprising contacting the first fluid, afterdiverting its flow from a first direction (e.g., upward) to a different,second direction (e.g., downward), with external surfaces of any of thecondenser tubes as described above and passing the second fluid throughthe tubes. In particular applications in which the tube bundles are usedas condensers, the first fluid is hotter than the second fluid, and afraction of this first fluid is condensed on external surfaces of thetube bundle.

A particular heat exchange application of commercial interest involvesthe use of the condenser tubes in internal condensers for vapor-liquidcontacting apparatuses such as distillation columns. Distillation refersto a separation process based on differences in the relative volatilityof components present in an impure mixture. Distillation involves thepurification of components having differing relative volatilities byachieving multiple theoretical stages of vapor-liquid equilibrium alongthe length of a vertical column. Rising vapor, enriched in a lowerboiling component relative to the liquid from which it is vaporized in alower stage in the column, is contacted with falling liquid, enriched ina higher boiling component relative to the vapor from which it iscondensed in a higher stage in the column.

Accordingly, particular embodiments of the invention are directed to theuse vapor flow-diverting devices as described above in combination withtube bundles comprising tubes as described above. The vaporflow-diverting devices and tube bundles are used in heat exchangerswithin vapor-liquid contacting apparatuses such as distillation columns.A first fluid comprising distillation column vapor, often rising in atop or overhead section of the column, is enriched in a lower boilingcomponent, the purification of which is the objective of thedistillation. The flow of this first fluid is diverted from the upwarddirection, using the vapor flow-diverting device, prior to contactingthis fluid with the external surfaces of the tubes or tube bundle (e.g.,to condense a liquid from this first fluid that is enriched in the lowerboiling component, relative to the impure mixture being fed into thecolumn and purified), while a second, cooling fluid (e.g., coolingwater) is passed through the tubes. As a result of contacting the firstfluid with the external surfaces of the tubes, a condensed liquid and anon-condensed vapor are formed. The non-condensed vapor may be removedfrom the column, while the condensed liquid is returned to animmediately lower contacting stage, for example as overhead reflux.

Other embodiments of the invention are directed to methods of purifyinga lower boiling component from an impure mixture by distillation. Themethods comprise condensing a liquid, enriched in the lower boilingcomponent, from a downwardly flowing vapor on the external surfaces ofthe condenser tubes in the co-current contacting section of theapparatus as defined above. Particular embodiments further compriseremoving the vapor from the column through the non-condensed vaporoutlet and returning the liquid to the column through the condensedliquid outlet. Any of the apparatuses and methods described above andbeneficially utilizing a vapor flow-directing device to provide aco-current contacting section of the tubes within the column, may beusing in conjunction with any of the surface enhancements, coatings(e.g., EBLs), and/or tube geometries as discussed previously.

These and other aspects and embodiments associated with the presentinvention are apparent from the following Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the upper section of a distillation column having aninternal tubular condenser, with the tubes extending vertically over asection of the column length.

FIG. 2 depicts the upper section of a distillation column having aninternal tubular condenser, with the tubes extending horizontally over aco-current contacting section within a vapor flow-directing device.

FIG. 3 depicts an end view of the upper section of the distillationcolumn shown in FIG. 2.

FIG. 4 depicts a representative internal tubular condenser, with thetubes extending horizontally over a co-current contacting section. Adivider plate is used to separate the co-current contacting section ofthe tubes from a horizontally adjacent vapor-liquid disengagementsection.

FIG. 5 depicts a representative section of a tube for a tubularcondenser, in which the tube has external surface enhancements in theform of circumferentially extending fins as discreet extensions.

FIG. 5A depicts a representative section of a tube for a tubularcondenser, in which the tube has external surface enhancements in theform of circumferentially extending fins as a single, continuouslywound, helical spiral.

FIG. 6 depicts a cross-sectional view of the tube section of FIG. 5,through A-A′.

FIG. 7A depicts a modification of the tube of FIGS. 5 and 6, in which aplurality of axially aligned notches, having a curved cross-sectionalshape, are included on outer edges of circumferentially extending fins.

FIG. 7B depicts a further modification of the tube of FIGS. 5 and 6, inwhich a plurality of axially aligned notches, having a triangularcross-sectional shape, are included on outer edges of circumferentiallyextending fins.

FIG. 7C depicts a representative section of a tube havingcircumferentially extending fins as shown in FIG. 7B, but with thenotches being bent at their respective corners outside of the plane ofthe circumferentially extending fins, and in opposite directions.

FIG. 8 depicts a representative section of a tube having surfaceenhancements in the form of small shaped recessions aligned in axiallyextending rows that alternate, about the radial tube periphery, withlarger, axially extending shaped recessions in the form of troughs, aswell as internal spiral ridges.

FIG. 9 depicts a representative section of a tube having surfaceenhancements in the form of axially extending shaped recessions ortroughs that form axially extending ridges resulting from the axialextension of sections or points of the external tube surface that do notform the recessions.

FIG. 10A depicts a cross-sectional view of a tube having surfaceenhancements in the form of axially extending shaped recessions having asemi-circular cross-sectional shape and spaced about the radial tubeperiphery.

FIG. 10B depicts a cross-sectional view of a tube having surfaceenhancements in the form of axially extending shaped recessions having atriangular cross-sectional shape and spaced about the radial tubeperiphery.

FIG. 10C depicts a cross-sectional view of a tube having surfaceenhancements including both axially extending shaped recessions, havinga notched, triangular cross-sectional shape, that form alternatingaxially extending ridges.

FIG. 10D depicts a cross-sectional view of a tube having surfaceenhancements in the form of axially extending shaped recessions having asemi-circular cross-sectional shape, with the axially extending ridgesformed between these shaped recessions also having a semi-circularcross-sectional shape.

FIG. 11 depicts a representative section of a tube having surfaceenhancements in the form of axially extending fins that are spaced aboutthe radial tube periphery.

FIG. 12 depicts a cross-sectional view of the tube section of FIG. 11,through A-A′.

FIG. 13A depicts a representative section of a tube having a twistedtube geometry as a tube enhancement.

FIG. 13B depicts a cross-sectional view of the tube of FIG. 13A.

The same reference numbers are used to illustrate the same or similarfeatures throughout the drawings. The drawings are to be understood topresent an illustration of the invention and/or principles involved. Asis readily apparent to one of skill in the art having knowledge of thepresent disclosure, vapor-liquid contacting apparatuses, andparticularly those comprising vertically oriented columns having tubularcondensers disposed therein, according to various other embodiments ofthe invention, will have configurations (e.g., a number of tube passes)and components determined, in part, by their specific use.

DETAILED DESCRIPTION

The invention is associated with improvements in heat exchangers andparticularly internal tubular condensers used in vapor-liquid contactingapparatuses such as distillation columns. Internal tubular condensers,often referred to the in art as “column installed” or “stabbed-in”tubular condensers when used to condense vapors generated indistillation, are normally installed in the upper vapor-liquidcontacting section of a column. These condensers may be installed eithervertically from the top, as shown in FIG. 1 or horizontally from theside, as shown in FIG. 2. References to tubes extending vertically orhorizontally are based on their general direction of orientation withrespect to a vertically or substantially vertically oriented column inwhich they are disposed. Therefore, vertically extending tubes willextend, over the majority of their length, in the same general directionas the axis of the column, while horizontally extending tubes willextend, over the majority of their length, in the direction generallyperpendicular to the axis of the column. Vertically or horizontallyextending condensers refer in particular to heat exchangers having atube bundle in which the tubes extend, respectively, vertically (orsubstantially vertically) or horizontally (or substantiallyhorizontally) over a section (e.g., a top or overhead section) of thecolumn length.

The use of tubular condensers within vapor-liquid contacting apparatusesis often economically attractive compared to external heat exchangers orinternal, welded plate exchangers. However, in conventional internaltubular condensers, vapor flows generally upwardly through the tubebundle, whether the bundle is arranged vertically or horizontally. Ineither case, but especially for horizontally aligned internal tubularcondensers, it is possible for vapor velocities in the upward directionto hold up or even re-entrain falling liquid condensate, therebyflooding the tube bundle and limiting its capacity. As discussed above,aspects of the invention are associated with the discovery of commercialbenefits that can result from diverting the vapor flow from itsgenerally upward flow direction in an overhead section of a column,prior to contacting this vapor with tubes of a tube bundle of aninternal condenser. In particular, diverting the flow of vapor(containing condensable material), can enhance the overall performanceof the condenser by reducing the detrimental entrainment of condensedliquid by otherwise upwardly flowing vapor and thereby improving thecondensed liquid/non-condensed vapor separation. The performance oftubular condensers may therefore be increased using devices thatbeneficially direct vapor flow in particular directions across, and/orin particular sections of, a tube bundle positioned within avapor-liquid contacting apparatus.

FIG. 1 shows an upper section of a distillation column 20 having aconventional internal tubular condenser 30, with a plurality of tubes 2extending vertically over a section 4 of the column length. It isrecognized that the entire length of the tube will generally not extendonly in one direction, but will normally curve, for example in a U-bend,as shown in FIG. 1, to redirect fluid passing through the tubes back toa common tube sheet 6 securing the two ends of each of the tubes so thatthey are in communication with respective tube-side inlet 8 and outlet10 conduits. During operation, upwardly flowing vapor 12 a in the uppersection of the distillation column 20 contacts tubes 2, through whichcooling fluid (e.g., cooling water) is passed from the tube-side inlet 8to the tube-side outlet 10. Contact between the relatively hot vapor 12a, comprising condensable material, and the relatively cool externalsurfaces of tubes 2 causes condensation, with condensed liquid fallingback into the column interior and non-condensed vapor exiting through anon-condensed vapor outlet 14 that may be in communication with thecolumn exterior. Both (i) the upwardly flowing vapor 12 a and (ii) thefraction of this upwardly flowing vapor 12 a that is the non-condensedvapor exiting the column are enriched, as a result of the distillation,in a lower boiling component initially present in an impure mixture.Compared to the upwardly flowing vapor 12 a within the column, thenon-condensed vapor exiting the column will normally be more enriched inthis component, as a result of removing additional, higher boilingimpurities through condensation. To improve contacting with tubes 2, theflow of upwardly-flowing vapor 12 a may be passed from one side of thecolumn 20 to the other side, using baffles 16, as it travels generallyupwardly through tube bundle.

Aspects of the invention are therefore directed to vapor flow-divertingdevices that can act as a shroud around the tube bundle and re-directvapor rising in the upper section of a vapor-liquid contacting device,such as from the top contacting stage of a distillation column,downwardly (rather than upwardly as shown in FIG. 1) through aco-current contacting section of the tubes in a tube bundle. Forexample, FIGS. 2 and 3 depict front and side views, respectively, of anupper section of a distillation column 20 containing a plurality ofcondenser tubes 2 in a horizontally aligned tube bundle (i.e., extendinghorizontally over a section 4 of the column length) of internal tubularcondenser 30. Also disposed within the column is a vapor flow-directingdevice 50 that has a vapor inlet 52 above the tubes, such that the flowof vapor 12 b is diverted downwardly through condenser tubes 2, causingvapor 12 b and liquid condensed from this vapor to flow co-currentlyacross the tube bundle. FIG. 3 illustrates a vapor inlet 52 having areduced inlet area, with the width of this area being smaller than thediameter of the tube bundle. Decreasing or increasing the area overwhich vapor enters into the interior of the vapor flow-directing device50 allows the velocity of the incoming vapor to be increased ordecreased, respectively. After contacting condenser tubes 2, theresulting condensed liquid and non-condensed vapor then pass below thebundle these tubes 2 to a vapor-liquid disengagement volume 54 definedwithin a lower portion of the vapor flow-directing device 50, as shownin FIGS. 2 and 3.

The vapor-liquid disengagement volume 54 provides a space for thesettled, condensed liquid and non-condensed vapor to separate. Both anon-condensed vapor outlet 14, directed externally to the column and acondensed liquid outlet 58, directed internally to the column (e.g.,back to an internal upper stage contacting device, such as a tray) arein communication with the vapor-liquid disengagement volume 54. FIGS. 2and 3 further illustrate the use of a deflector plate 56 below the tubesand within the vapor-liquid disengagement volume 54, to aid theseparation of vapor and liquid exiting the tube bundle co-currently. Thedeflector plate 56 may extend horizontally or may be inclined relativeto horizontal, in order to improve drainage of condensed liquid in thedisengagement volume 54 and ultimately to condensed liquid outlet 58.Condensed liquid outlet 58 may be operated with a liquid seal providedby draining, condensed liquid to prevent vapors in the upper section ofcolumn 20 from entering into the interior of vapor flow-directing device50 upwardly through condensed liquid outlet 58.

An alternative embodiment is illustrated in FIG. 4, where a dividerplate 59 extends vertically into the vapor flow-directing device 50 anddivides a co-current contacting section of the tubes, in a contactingvolume 60, from a disengagement section of the tubes, in thevapor-liquid disengagement volume 54 a. In this case, vapor inlet 52 islocated above the co-current contacting section of the tubes 2, whilethe disengagement section of the tubes receives the non-condensed vaporonly after it passes in a downwardly flowing direction across theco-current contacting section of the tubes 2. Divider plate 59, in theconfiguration of FIG. 4, therefore causes non-condensed vapor exitingcontacting volume 60 to reverse flow again, flowing generally upwardlythrough disengagement volume 54 a prior to exiting the non-condensedvapor outlet 14. Divider plate 59 can therefore advantageously reducethe vapor-liquid disengagement volume 54 below the tube bundle andinstead allow some of this volume to be positioned horizontally adjacentthe contacting volume 60.

Thus, features described above include (i) the vapor flow-divertingdevice, which substantially surrounds (e.g., on three sides) the tubebundle and diverts vapor flow to the top of the bundle and downwardtherethrough, and (ii) the vapor-liquid disengagement volume defined bythe vapor flow-diverting device, optionally in conjunction with adivider plate that provides separate (e.g., horizontally spaced apart)sections of the tube bundle for contacting and disengagement of thecondensed liquid from the non-condensed vapor. These features canimprove the performance of tubular heat exchanges and particularly thosewhich are internal to vapor-liquid contacting apparatuses (e.g.,internal distillation column condensers) by mitigating or eliminatingflooding concerns, particularly in the tube bundles, enhancing heattransfer by improving vapor and liquid flow over the bundles, and/orproviding improved vapor-liquid disengagement. Those having skill in theart will appreciate that changing the sizes and locations of theco-current contacting section and the vapor-liquid disengagementsection, as well as the positions of the inlets to and outlets from, thevapor flow-diverting device (e.g., the non-condensed vapor outlet andcondensed liquid outlet) can be used to create various flow paths ofvapor and liquid across the condenser tubes, to further optimize theperformance of the tubular condenser in terms of its heat transfercoefficient and thereby minimize its size. For example, it may bedesired to use a vapor-flow diverting device to direct incoming vapor ina horizontal direction, or in an inclined direction, across the tubes ofa tube bundle.

In addition to these improvements, tubes having one or more surfaceenhancements as discussed above may be used to effectively improve theirheat transfer coefficient when used in combination with a vaporflow-diverting device and optionally a deflector plate and/or dividerplate. These external surface enhancements may optionally be combinedwith an internal surface coating and/or non-linear or twistedgeometries, also as discussed above, to further improve the tubeperformance. The various tube surface enhancements described herein mayserve, alone or in combination, to facilitate this condensate drainageand/or reduce the layer thickness of formed condensate. Inrepresentative embodiments, for example, the use of such surfaceenhancement(s) will generally increase the tube heat transfercoefficient in a given condensing service (e.g., in a distillationcolumn used in the product recovery section in the commercial productionof phenol via cumene oxidation) by a factor of at least about 1.5,typically from about 2 to about 10, and often from about 3 to about 5,relative to the heat transfer coefficient obtained with identical tubesbut lacking the surface enhancement(s).

As discussed above, this improvement in heat transfer coefficientdecreases the tube area needed, such that tubular condensers employingthese enhancements can be feasibly installed in larger-diameterdistillation columns, for example those having a diameter of generallygreater than about 0.9 meters (3 feet), typically in the range fromabout 1.07 meters (3.5 feet) to about 6.10 meters (20 feet), and oftenin the range from about 1.22 (4 feet) to about 4.88 meters (16 feet).The use of tube bundles in tubular condensers, in which at least aportion of the individual tubes have surface enhancements as describedherein, may in some cases provide an economically attractivealternative, relative to external condensers or even welded plate,internal condensers. Any of the tubes described below, having surfaceenhancements, will generally have an outer diameter in the range fromabout 13 mm (0.5 inches) to about 38 mm (1.5 inches), and often fromabout 19 mm (0.75 inches) to about 32 mm (1.25 inches). The innerdiameters of such tubes are generally in the range from about 6 mm (0.25inches) to about 32 mm (1.25 inches), and often from about 13 mm (0.5inches) to about 25 mm (1 inch). The inner and outer diameters can bedetermined and/or optimized for a given service based on a number offactors, including the design flow rates, pressure drops, and heattransfer coefficients, as will be appreciated by those having skill inthe art and knowledge of the present disclosure.

Any of the tube enhancements, including internal enhancements, as wellas different tube geometries (e.g., twisted tubes) described herein areapplicable to internal condensers having vertically extending tubes asdepicted in FIG. 1, as well as those having horizontally extending tubesas depicted in FIG. 4. In the case of internal distillation columncondensers having vertically (or substantially vertically) orhorizontally (or substantially horizontally) oriented condenser tubes,surface enhancements, in at least the region of the tubes extending overa section of the column length, include circumferentially extendingfins, as illustrated in FIG. 5. FIG. 5A shows circumferentiallyextending fins 15 a provided by a single, continuously wound, helicalspiral rather than discreet extensions, as shown in FIG. 5. In the caseof tubes 2 comprising circumferentially extending fins 15 a, a finheight of less than about 6.4 mm (0.25 inches) is representative, withfin heights typically being in the range from about 0.51 mm (0.02inches) to about 5.1 mm (0.20 inches), and often being in the range fromabout 0.76 mm (0.03 inches) to about 3.8 mm (0.15 inches). As isillustrated in the cross-sectional view of FIG. 6, circumferentiallyextending fins 15 a may be in the form of flat plates or discs having acircular cross section that is concentric with circular cross sectionsof internal surface 25 and external surface 27 with these cross sectionsbeing circles with inner and outer diameters, respectively, of tubes 2.The fin height can therefore be measured as the distance from theexternal surface 27 of a tube 2 to the outer edge 29 ofcircumferentially extending fin 15 a. In cases where the fins havegeometries that are not circular (e.g., elliptical or rectangular),where the fin cross sectional shape is not concentric with the centralaxis of the tube 2, or where the tube 2 itself has a non-circular (e.g.,flattened or elliptical) cross section, the fin height may be theaverage distance from the outer edge 29 of circumferentially extendingfin 15 a to the external surface 27 of tube 2.

FIG. 7A shows a cross-sectional view of a tube 2 having surfaceenhancements in the form of fins 15 a, as shown in FIGS. 5 and 6. In theembodiment illustrated in FIG. 7A, however, a plurality of notches 35are “cut” from, or shaped in, the outer edges 29 of fins 15 a. Notches35 shown in FIG. 7A have a curved cross-sectional shape (e.g.,semi-circular), but other curved cross-sectional shapes or rectangularcross-sectional shapes may be used for notches 35. For example, FIG. 7Bshows notches 35 having a triangular cross-sectional shape. Also asillustrated in FIGS. 7A and 7B, notches may be spaced evenly about theouter edge 29 or periphery of fin 15 a. In a particular embodiment, inwhich circumferentially extending fins 15 a, as surface enhancements,have outer edges 29 that include notches 35 having a triangular (orother) cross-sectional shape, these notches 35 may be bent at theirrespective corners 37 outside of the plane of the circumferentiallyextending fins, for example opposing corners 37 of a triangular crosssection may be bent in the same or opposite directions. In theparticular embodiment illustrated in FIG. 7C, for example, these notches35 are bent at their respective corners 37 in opposite directions. In apreferred embodiment, and particularly in the case in which the tubesare used in vertical, column-installed condensers, all or a portion ofnotches 35, whether or not they are bent, may be aligned axially, withone or more corresponding notch(es) in the outer edge of one or bothadjacent circumferentially extending fins (e.g., in both of thecircumferentially extending fins located immediately above andimmediately below, in the case of a vertically extending tube). Axialalignment of notches is also illustrated in the representativeembodiment of FIG. 7C. This axial alignment of notches can promoteimproved drainage of condensate from the tubes, particularly in thevertical direction.

In the same manner as described above with respect to notches on outeredges of fins, notches or recessions having various cross-sectionalshapes may be formed directly on the outer surfaces of heat exchangertubes to provide surface enhancements. Extending these notches in theaxial direction on the tube surface results in elongated troughs aboutthe tube periphery. Alternatively, discreet, shaped recessions may beformed on the external tube surface. While the recessions themselves maybe small, if desired, in order to provide an effective capillary actionthat reduces condensate layer thickness, such smaller recessions may bealigned axially to provide an axial or generally axial flow path forcondensed liquid. FIG. 8 depicts tubes 2 having shaped recessions 36 a,36 b on the external surface, where a portion of these recessions 36 aare smaller and are aligned in axially extending rows 22 a, for example,with outer edges of the recessions in a row 22 a forming a line thatextends axially along the external surface of the tube. As discussedabove, these smaller, discreet shaped recessions 36 a on the tubesurface can act as capillaries, such that the surface tension of thecondensed liquid is drawn into recessions 36 a. In a representativeembodiment, in order to provide capillary action, each individual shapedrecession will normally have only a small area, typically less thanabout 5 mm² (7.8×10⁻³ in²) and often in the range from about 0.1 mm²(1.6×10⁻⁴ in²) to about 4 mm² (6.2×10⁻³ in²). Aligning at least some ofthe recessions in one or more axially extending rows may improvedrainage of the condensed liquid, particularly in the case of avertically extending internal tubular condenser. In the embodiment shownin FIG. 8, the axially aligned, smaller, discreet shaped recessions 36 aare used as surface enhancements in combination with axially elongatedshaped recessions 36 b (i.e., with the individual recessions extendingover a longer axial portion). Both of these surface enhancements may beused in a common region of the tube that extends over a section of thelength of a distillation column where condensation occurs. In theparticular embodiment illustrated in FIG. 8, rows 22 a of discreet,shaped recessions 36 a alternate radially about the tube periphery withrows 22 b of larger, axially extending shaped recessions 36 b (e.g., inthe form of troughs), between which rows the external surface 27 of tube2 may be smooth. FIG. 8 also depicts internal enhancements on internalsurface 25, namely spiral ridges 21, which may be used for improved heatexchange. In FIG. 9, the axially extending, shaped recessions 36 b arein the form of troughs having a triangular cross-sectional shape.

FIGS. 10A-10C illustrate in more detail some representative crosssections of tubes having shaped recessions 36 on their external surfaces27. In particular, the shaped recessions 36 in FIG. 10A have a curvedcross-sectional shape that is semi-circular, while the shaped recessions36 in FIG. 10B have a triangular cross-sectional shape. Other curved andrectangular (e.g., semi-elliptical and square) cross-sectional shapesare possible. Another embodiment in which tube surfaces are enhancedwith shaped recessions 36 is shown in FIG. 10C, where, as in FIG. 10B,the cross-sectional shapes of recessions 36, spaced (e.g., uniformly)about the periphery of the surface of tube 2, are triangles. In theembodiment shown in FIG. 10C, however, these triangles are broad enoughsuch that only small sections or points of the external surface 27 oftube 2 remain (or are not part of the shaped recessions), with thesesections being spaced radially about the periphery of tube 2. The axialextension of these sections or points results in axially extendingridges. Such a tube with axially extending, shaped recessions 36 b ortroughs aligned in axial rows 22 b is also illustrated in the front viewof FIG. 9.

In FIG. 10D, the axially extending ridges, similarly formed betweenthese shaped recessions, have a smooth, curved (e.g., semi-circular)cross-sectional shape of the same or similar dimension as the curvedcross sectional shape forming the shaped recessions. The cross sectionalshape of this tube therefore has a generally circular perimeter definedby alternating, concave and convex curves (e.g., semi-circles). Theresulting, smooth external surface contrasts with the embodiment shownin FIG. 10A, where the shaped recessions form edges. Therefore, asshown, for example in the embodiment of FIG. 10D, the shaped recessionscan provide a fluted profile of a fluted tube. Fluted tubes or othertubes having axially extending shaped recessions or discreet, shapedrecessions aligned in axially extending rows as depicted, for example,in FIGS. 10A-10D may be characterized as having two outer diameters.Smaller and larger outer diameters may be the distances, respectively,to opposing deepest points of recessions 36 and opposing externalsurfaces 27, with each of these distances being measured through thecenter of the cross section of tube 2. Representative tubes havingaxially extending shaped recessions will have smaller and larger outerdiameters in the ranges from about 13 mm (0.5 inches) to about 32 mm(1.25 inches) and from about 19 mm (0.75 inches) to about 38 mm (1.5inches), respectively. In exemplary embodiments, such a tube will haveouter diameters of about 19 mm (0.75 inches) and about 25 mm (1.0inches) or outer diameters of about 25 mm (1.0 inches) and about 32 mm(1.25 inches).

Additional surface enhancements to improve heat transfer for verticallyextending tubes are shown in FIG. 11, which depicts tubes having aplurality of axially extending fins 15 b that may, for example, be inthe form of flat plates raised above the external surface 27 of the tube2 and extending axially along the length of the tube. Representativefins may have a fin height as described above with respect to theheights of circumferentially extending fins, with the fin height alsobeing based on the distance (or average distance) between the outer edge29 of axially extending fin 15 b and the external surface 27 of tube 2.Otherwise, the fin heights of axially extending fins may be relativelyhigher, for example with ranges from about 3.2 mm (0.125 inches) toabout 25 mm (1 inch), and often from about 6.4 mm (0.50 inches) to about19 mm (0.75 inches) being representative.

A cross-sectional view of the tube shown in FIG. 11, having a pluralityof axially extending fins 15 b, in this case spaced uniformly about theradial periphery of the tube 2, is shown in FIG. 12. As discussed abovewith respect to circumferentially extending fins (15 a in FIG. 5),axially extending fins 15 b may also have notches with variouscross-sectional shapes. FIG. 13A illustrates a tube having a twistedtube geometry to provide an overall helical fluid flow path within thetube. As seen in the cross-sectional view of FIG. 13B the eccentricprofile tube has an oval-shaped cross section 50, with the major axis 55that rotates clockwise or counterclockwise along the linear direction ofthe tube).

Any of the axially extending features (i.e., in the same orsubstantially the same direction as the central axis of the tube)discussed above, such as axially extending shaped recessions, axiallyextending rows of shaped recessions, or axially extending fins, aretherefore vertically or horizontally extending features, depending onwhether the tubes are aligned vertically or horizontally, respectively.In alternative embodiments, any of the described, axially extendingfeatures may extend or be aligned generally in the axial direction alongthe length of the external surface of the tube, in a non-linear pathsuch as a wave, spiral, jagged line, etc. Such embodiments provide agenerally axial flow path (e.g., corresponding to the downward flow pathof condensed liquid along the tube when positioned vertically) for fluidcontacting the heat exchange surface, where this flow path provided bythe features is not directly, but only generally, axially.

The use of axially or generally extending shaped recessions and/or fins,in this manner, as tube surface enhancements, can reduce condensate filmthickness and/or facilitate condensate drainage, thereby improving theheat transfer coefficient of the tube. Such features as surfaceenhancements for tubes are particularly advantageous in internal tubularcondensers (e.g., disposed in distillation columns), where the heatexchange surface area, as well as the total weight of equipment that canbe practically installed (e.g., at or near the top of the column ortower), is limited. The tube surface enhancements discussed above may beused alone or in combination. The tube surface enhancements may also beused in combination with internal enhancements as discussed above, andparticularly spiral ridges that may act to further improve heattransfer. Otherwise, these surface enhancements may be combined with acoating, such as a porous metallic matrix used to form an enhancedboiling layer as discussed above, that is bonded onto internal surfacesof the tubes, for example, in at least the same region of the tubes(e.g. extending over a section of the column height) as the surfaceenhancements. The surface enhancements may also be used in tube bundlesin which all or a portion of the tubes have a non-linear central axis(e.g., a helical axis), or otherwise have a twisted tube geometry asdiscussed above, in at least the same region of the tubes as the surfaceenhancements. In a representative embodiment, for example, a tube bundleof a condenser, having tubes with a fluted tube profile and an internalenhancement including one or more spiral ridges, is aligned verticallyin the upper section of a distillation column. Various othercombinations of surface enhancements, optionally with an internalsurface coating and/or non-linear or twisted geometries, can beincorporated into tubes to improve their heat transfer coefficient,particularly when the tubes are used in a tube bundle that is orientedvertically and used in a service in which condensate drains verticallyfrom the external surfaces of the tubes (i.e., on the “shell side” ofthe condenser).

Overall, aspects of the invention are directed to improvements in heatexchangers and particularly tubular exchangers oriented horizontally orvertically within contacting apparatuses such as distillation columns.Those having skill in the art, with the knowledge gained from thepresent disclosure, will recognize that various changes can be made inthe above apparatuses, heat exchangers, tubes, and vapor-liquidcontacting (e.g., distillation) methods without departing from the scopeof the present disclosure. Mechanisms used to explain theoretical orobserved phenomena or results, shall be interpreted as illustrative onlyand not limiting in any way the scope of the appended claims.

1. An apparatus for vapor-liquid contacting, comprising: a verticallyoriented column having disposed therein a plurality of condenser tubesfor passing cooling fluid therethrough, wherein the condenser tubesextend substantially vertically; an upper section of the verticallyoriented column configured for receiving vapor rising upwardly from alower contacting section of the vertically oriented column; a vaporoutlet external to the column and in communication with the uppersection of the vertically oriented column; and a plurality of bafflesfor redirecting the upwardly rising vapor across the condenser tubessuch that the vapor passes in a first substantially horizontal directionand then in a second substantially horizontal direction as the vaportravels generally upwardly.
 2. The apparatus of claim 1, wherein thefirst substantially horizontal direction is opposite of the secondsubstantially horizontal direction.
 3. The apparatus of claim 1, whereineach of the baffles extends only partially across the verticallyoriented column.
 4. The apparatus of claim 1, further comprising: avapor flow-directing device disposed within the column and having avapor inlet above at least a co-current contacting section of the tubesand defining a vapor-liquid disengagement volume; a cooling fluid inletconduit in communication with the condenser tubes; and a cooling fluidoutlet conduit in communication with the condenser tubes, wherein thecooling fluid inlet and the cooling fluid outlet are located above thecondenser tubes.
 5. The apparatus of claim 4, wherein the condensertubes include U-bend portions therein.
 6. The apparatus of claim 5,further comprising a common tube sheet for securing both ends of each ofsaid condenser tubes at a location below said cooling fluid inletconduit and said cooling fluid outlet conduit.
 7. An apparatus forvapor-liquid contacting, comprising: a vertically oriented column havingdisposed therein a plurality of condenser tubes; a vapor flow-directingdevice disposed within the column and having a vapor inlet above atleast a co-current contacting section of the tubes and defining avapor-liquid disengagement volume; a non-condensed vapor outlet externalto the column and in communication with the vapor-liquid disengagementvolume; a condensed liquid outlet internal to the column and incommunication with the vapor-liquid disengagement volume; and whereinthe condenser tubes extend substantially vertically.
 8. The apparatus ofclaim 7, further comprising a plurality of baffles for redirecting thedownwardly moving vapor across the condenser tubes such that the vaporpasses in a first direction and then passes in a second direction. 9.The apparatus of claim 7, wherein at least a portion of the condensertubes have external surfaces comprising one or more surfaceenhancements.
 10. The apparatus of claim 8, wherein the surfaceenhancements comprise shaped recessions, circumferentially extendingfins, or a combination thereof.
 11. The apparatus of claim 10, whereinthe shaped recessions provide a fluted profile.
 12. The apparatus ofclaim 7, wherein at least a portion of the tubes further comprise aninternal enhancement in the form of one or more spiral ridges.
 13. Theapparatus of claim 7, wherein at least a portion of the tubes haveinternal surfaces having a porous metallic matrix bonded thereon.
 14. Anapparatus for vapor-liquid contacting, comprising: a vertically orientedcolumn having disposed therein a plurality of condenser tubes; an uppersection of the vertically oriented column configured for receiving vaporrising upwardly from a lower contacting section of the column; a vaporflow-directing device disposed within the column and having a vaporinlet above at least a co-current contacting section of the tubes anddefining a vapor-liquid disengagement volume, wherein the vapor inlet isin fluid communication with the upper section of the column forredirecting at least a portion of the vapor rising in the upper sectiondownwardly through the co-current contacting section of the tubes andwherein the vapor-liquid disengagement section volume is below thetubes; a non-condensed vapor outlet external to the column and incommunication with the vapor-liquid disengagement volume; and acondensed liquid outlet internal to the column and in communication withthe vapor-liquid disengagement volume, wherein the vapor flow directingdevice substantially surrounds the co-current contacting section of thetubes on three sides thereof, while allowing the vapor rising to theupper section of the column to pass upwardly between said vaporflow-directing device and the column along said three sides.
 15. Theapparatus of claim 14, further comprising a deflector plate below thetubes and within the vapor-liquid disengagement volume, and wherein thedeflector plate is above the non-condensed vapor outlet and extendshorizontally or at an incline.
 16. The apparatus of claim 14, wherein atleast a portion of the condenser tubes have external surfaces comprisingone or more surface enhancements.
 17. The apparatus of claim 16, whereinthe surface enhancements comprise shaped recessions, circumferentiallyextending fins, or a combination thereof.
 18. The apparatus of claim 16,wherein: the surface enhancements comprise circumferentially extendingfins having outer edges that include a plurality of notches; and theportion of the tubes having surface enhancements further comprise aninternal enhancement in the form of one or more spiral ridges.
 19. Theapparatus of claim 14, wherein at least a portion of the tubes haveinternal surfaces having a porous metallic matrix bonded thereon. 20.The apparatus of claim 14, wherein at least a portion of the condensertubes have a twisted tube geometry.